There are mainly three types of conventional energy-saving glasses, which are film-attached glass, laminated glass, and double-layered glass. The film-attached glass is made by attaching an energy-saving film, such as a heat reflecting or absorbing film, to a glass substrate. The laminated glass is made by disposing an energy-saving adhesive between two glass substrates. The double-layered glass is made by forming a vacuum space between two glass substrates, in which the vacuum space can block heat transfer and may receive an energy-saving film therein for better energy-saving performance.
The energy-saving film and energy-saving adhesive can absorb or reflect infrared and ultraviolet lights, and allow visible light to pass therethrough to achieve the purpose of energy-saving. The material and the thickness of the energy-saving film and energy-saving adhesive may be changed according to practical requirements. However, the thickness only affects the absorbing efficiency, and the wavelength of the light that is to be absorbed is determined by the material of the energy-saving film and energy-saving adhesive.
Another conventional energy-saving glass includes a glass substrate and a periodic metal layer formed thereon. A common design of the periodic metal layer is to form a two dimensional matrix composed of a plurality of metal squares. As a result, there are six factors affecting the properties of the periodic metal layer, i.e., the material and the thickness of the periodic metal layer, the length of each of the metal squares, the width of each of the metal squares, the spacing between adjacent two of the metal squares in the lengthwise direction, and the spacing between adjacent two of the metal squares in the widthwise direction. In practice, before the glass is manufactured, a simulating calculation will be conducted based on the aforesaid factors to determine the energy-saving efficiency. However, the multiple factors may impose complexity or even difficulty in simulating calculation. Moreover, the sharp corners of the metal squares may not be properly manufactured, and may lead to deficiency of the metal squares.